i2c: rcar: add rcar-H2 support

This patch modify I2C driver of rcar-H1 to usable on both rcar-H1 and rcar-H2.

Signed-off-by: Nguyen Viet Dung <nv-dung@jinso.co.jp>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>